The present invention relates to a novel state detecting device for detecting states such as charge condition, residual capacity in a power storage means such as a lithium secondary battery, a nickel hydride battery, a lead seal battery, an electric double layer capacitor, and to a power source unit, a distribution type power storage device, and an electric vehicle which use the state detecting device.
In a power source unit, a distribution type power storage device and an electric vehicle employing power storage means, such as a battery, a state detecting device is employed for detecting state of the power storage means in order to safely and effectively use the power storage means. The state of the power storage means represents state of charge (hereinafter abbreviated as “SOC” indicative how much charged or how much dischargeable charge amount resides, residual capacity, or state of health (hereinafter abbreviated as “SOH”) indicative of how much exhausted or weakened or degree of deterioration.
The SOC in the power source unit of a portable equipment, an electric vehicle and so forth can be detected by integrating a discharge current from a fully charged state and calculating a ratio of a charge amount residing in the power storage means (hereinafter referred to as “residual capacity”) versus a maximum chargeable charge amount (hereinafter referred to as “full capacity”). However, many power storage means varies the full capacities depending upon SOH, temperature and so forth, it is difficult to accurately detect SOC with respect to secular change and variation of environment.
In order to solve such problem, as conventional residual capacity predicting method in consideration of deterioration of battery, there has been known one disclosed in Japanese Patent Application Laid-Open No. Heisei 10-289734. FIG. 10 is an illustration showing a residual capacity predicting method of the above-identified publication. In this method, an initial battery characteristics is corrected by a temperature correction coefficient derived on the basis of a temperature of the battery and a deterioration correction coefficient derived based on deterioration of the battery, and a residual capacity of the battery is derived on the basis of the corrected battery characteristics, a discharge current during discharging and a terminal voltage.
In Japanese Patent Application Laid-Open No. Heisei 11-218567, there is shown a method for deriving a battery characteristics upon occurrence of deterioration by correcting an initial battery characteristics in relation to a temperature correction coefficient, an internal resistor deterioration correction coefficient, a capacitor deterioration correction coefficient.
In Japanese Patent Application Laid-Open No. 2000-166105, there has been disclosed a control unit detecting a charge condition on the basis of charge and discharge current, detecting a power storage condition on the basis of a voltage and controlling a charge condition on the basis of such detections.
In Japanese Patent Application Laid-Open No. 2000-166109, there has been disclosed a charge condition detecting device deriving an electromotive force based on a charge and discharge current and voltage and having a calculating means for deriving a charge characteristics on the basis of the electromotive force and the charge characteristics.
In Japanese Patent Application Laid-Open No. 2001-85071, there is disclosed a temperature detecting device predicting respective temperatures of a set battery modules on the basis of voltages between terminals and currents flowing therethrough.
In the residual capacity predicting method disclosed in the foregoing Japanese Patent Application Laid-Open No. Heisei 10-289734, in consideration of influence for temperature or deterioration, these influences are taken in as temperature correction coefficient or deterioration correction coefficient for correcting parameters necessary for calculation of the residual capacity with these correction coefficients derived through complicate derivation processes. Therefore, it is concerned whether the value per se of the correction coefficient is correct or whether all battery characteristics are corrected.
In addition, the power storage means of some kind also has characteristics, such as charge efficiency, memory effect and so forth, and is required to make correction in consideration of these characteristics in precision of residual capacity with high precision. On the other hand, the initial characteristics of the power storage mean generally contain individual difference. Correction for individual difference is also necessary in prediction of residual capacity with high precision.
Namely, in order to perform state detection, such as prediction of residual capacity with high precision, it becomes necessary to effect accurate modeling of the characteristics to take in a plurality of parameters. Furthermore, it is required to perform correction associated with secular change or environmental variation of these parameters.
Therefore, significant time and attention have to be paid for obtaining the initial characteristics and a plurality of parameters of the power storage means. However, no matter how complicated it is, the result of arithmetic operation is nothing but prediction on the basis of the theory or model of the battery characteristics. Therefore, it is stilled concerned whether the result of prediction is correct with respect to a true value.
Therefore, it has been found that, in order to realize state detection of the power storage means at high precision and simply in calculation with characteristic data to be used in arithmetic operation, correction by comparing the result of state detection with the true value or logic and feeding back to subsequent arithmetic operation with learning the difference, is required, and break through thereof is necessary. Since it is not possible to directly measure the state of the battery, such as SOC or SCH, an important problem is how to derive the true value or logic.
On the other hand, in Japanese Patent Application Laid-Open No. Heisei 11-218567, Japanese Patent Application Laid-Open No. 2000-166105, Japanese Patent Application Laid-Open No. 20000-166109 and Japanese Patent Application Laid-Open No. 2001-85071, it is failed to disclose to perform correction feeding back a correction information obtained through arithmetic operation to subsequent arithmetic operation, and to correct storage information necessary for the arithmetic operation, and to perform state detection of the power storage means on the basis of a plurality of particular arithmetic operation and a plurality of varying information.